Method and system for generating digital video broadcast (DVB) transport stream from direct satellite system (DSS) transport stream

ABSTRACT

Aspects of the method and system for converting a DSS transport stream to a DVB transport stream include encapsulating at least a prefix portion and a payload portion of a DSS transport packet into at least a header portion and a payload portion of a DVB transport packet. At least a portion of the prefix portion and the payload portion of the DSS transport packet may be mapped into at least a portion of the header portion and the payload portion of the DVB transport packet. At least a portion of the payload of the DSS transport packet may be aligned with at least a portion of the payload portion of the DVB transport packet.

RELATED APPLICATIONS

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FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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MICROFICHE/COPYRIGHT REFERENCE

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BACKGROUND OF THE INVENTION

Embodiments of the present application relate generally to broadbandpacket transport and distribution, and more particularly to a method andsystem for generating a digital video broadcast (DVB) transport streamfrom a direct satellite system (DSS) transport stream.

The introduction of broadband networks, access devices such as set-topboxes, and media such as DVD disks recorded with digitally compressedaudio, video and data signals, for example, which utilize motion PictureExpert Group (MPEG) compression protocols, may provide sound and picturequality that is virtually indistinguishable from the original material.The latest MPEG protocol called MPEG-2, provides the necessary protocolsand infrastructure that may be used for transferring digitallycompressed audio, video and data signals over various media. A detaileddescription of the MPEG-2 standard is published as ISO/IEC Standard13818-2. As broadband networks continue to evolve, there is a need toprovide access for legacy devices to ensure interoperability with legacyand disparate systems.

Satellite based systems have been utilized for decades to providepoint-to-multipoint communications. Satellite based systems generallyinclude an earth station which transmits microwave signals to anorbiting satellite. The orbiting satellite may be adapted to receive themicrowave signals from the earth station, amplify the received microwavesignals and transmit resulting amplified signals back towards earth orother orbiting satellites. In this regard, the satellite is adapted tofunction as a repeater and/or signal regenerator. Although satelliteshave been around for decades, the lack of standardized communicationtechnologies, compounded with factors such as signal latency, high costand immunity to atmospheric interference have resulted in low marketpenetration. Notwithstanding, advancements and standardization insatellite based communication technologies have created newopportunities that will result in greater market penetration. Forexample, advancements in open standards such as digital video broadcast(DVB) satellite standards and DVB data standard for Internet protocol(IP) have created opportunities for the efficient communication ofstreaming media to remote sites located throughout the globe.

The existence of proprietary and standardized satellite communicationtechnologies provides a need for concurrent support of proprietarysystems, legacy systems and/or systems that utilize the standardizedcommunication technologies. For example, DirecTV which broadcastsdigital television (DTV) programs utilizes a proprietary directsatellite system (DSS) transport stream, which has a packet format of130 bytes per packet, including prefix and payload bytes. Today'sstandardized set-top boxes are designed to support DVB standard MPEGtransport streams and do not provide support for the 130 bytes perpacket DSS proprietary transport stream.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with the present invention as set forth inthe remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

Aspects of the present invention provide a method and system forconverting a DSS transport stream to a DVB transport stream. The methodmay include encapsulating at least a prefix portion and a payloadportion of a DSS transport stream packet into at least a header portionand a payload portion of a DVB transport stream packet. At least aportion of the prefix portion and the payload portion of the DSStransport stream packet may be mapped into at least a portion of theheader portion and the payload portion of the DVB transport streampacket. At least a portion of the payload of the DSS transport streampacket may be aligned with at least a portion of the payload portion ofthe DVB transport stream packet.

The encapsulating step may further include the step of creating anadaptation field within at least a portion of the header portion of theDVB transport stream packet. The adaptation field may be at least fiftysix (56) bytes in size. The mapping step may further include mapping atleast an SCID of the DSS transport stream packet into a PID of the DVBtransport stream packet. The mapping step may further include mapping atleast an RTS of the DSS transport stream packet into a PCR of the DVBtransport stream packet. The mapping step may further include the stepof mapping at least a PTS and DTS resolution of the DSS transport streampacket into a corresponding PTS and DTS resolution of the DVB transportstream packet.

The aligning step may further include the step of locating PES headersin the DSS transport stream packet and validating the located PESheaders to ensure that the headers are synchronous with transportheaders of the DSS transport stream packet. The method for converting aDSS transport stream to a DVB transport stream may further include thestep of inserting at least one null packet in at least one of the headerportion and the payload portion of the DVB transport stream packet tomaintain a specified data rate.

In another embodiment of the invention, a machine-readable storage,having stored thereon a computer program having at least one codesection for converting a DSS transport stream to a DVB transport stream,the at least one code section executable by a machine for causing themachine to perform the steps described above.

Another embodiment of the invention provides a system for converting aDSS transport stream to a DVB transport stream. The system may includeat least one encapsulator adapted to encapsulate at least a prefixportion and a payload portion of a DSS transport stream packet into atleast a header portion and a payload portion of a DVB transport streampacket. At least one mapper may be adapted to map at least a portion ofthe prefix portion and the payload portion of the DSS transport streampacket into at least a portion of the header portion and the payloadportion of the DVB transport stream packet. At least one aligner may beadapted to align at least a portion of the payload of the DSS transportstream packet with at least a portion of the payload portion of the DVBtransport stream packet.

The at least one encapsulator may be further adapted to create anadaptation field within at least a portion of the header portion of theDVB transport stream packet. In accordance with an aspect of theinvention, the adaptation field may be at least fifty six (56) bytes insize. The at least one mapper may be further adapted to map at least anSCID of the DSS transport stream packet into a PID of the DVB transportstream packet. The at least one mapper may be further adapted to map atleast an RTS of the DSS transport stream packet into a PCR of the DVBtransport stream packet. The at least one mapper may be further adaptedto map at least a PTS and DTS resolution of the DSS transport streampacket into a corresponding PTS and DTS resolution of the DVB transportstream packet. The at least one aligner may further include a locatoradapted to locate PES headers in the DSS transport stream packet and avalidator adapted to validate the located PES headers to ensure that theheaders are synchronous with transport headers of the DSS transportstream packet. Finally, a null packet generator may be provided toinsert at least one null packet in the header portion and/or the payloadportion of the DVB transport stream packet to maintain a specified datarate.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram of the structure for an exemplary MPEG transportstream.

FIG. 1A is a block diagram of an exemplary MPEG encoding system.

FIG. 1B is a block diagram of an exemplary MPEG decoding system.

FIG. 2 is block diagram illustrating an exemplary DSS transport streampacket.

FIG. 3 is block diagram illustrating the conversion of a DSS transportstream packet to a DVB transport stream packet in accordance with anembodiment of the present invention.

FIG. 4 is a block diagram of an exemplary system for converting a DSStransport stream to a DVB transport stream in accordance with anembodiment of the invention.

FIG. 5 is an block diagram of an exemplary video buffer 510 arrangementand an exemplary audio buffer 520 arrangement in accordance with anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the method and system for converting a DSS transport streamto a DVB transport stream include encapsulating at least a prefixportion and a payload portion of a DSS transport packet into at least aheader portion and a payload portion of a DVB transport packet. At leasta portion of the prefix portion and the payload portion of the DSStransport packet may be mapped into at least a portion of the headerportion and the payload portion of the DVB transport packet. At least aportion of the payload of the DSS transport packet may be aligned withat least a portion of the payload portion of the DVB transport packet.

Given the current mixture of standardized, proprietary and legacytechnologies, conversion methodologies are required to provide devicecompatibility and interoperability. In some applications, for example,an access device such as a set-top box may require the conversion of DSSproprietary transport streams to standardized DVB transport streams inorder to communicate with a standardized external MPEG devices, such asa personal video recorders (PVRs) or a high definition televisions(HDTVs). In order to provide compatibility and interoperability betweenproprietary and legacy systems, and standardized DVB MPEG compliantsystems, it may be necessary for conversion of the transport stream tomeet one or more of the following requirements. Any resulting transportstream should be fully MPEG2 DVB compliant, since a set-top box may lacka priori knowledge pertaining to a type of external MPEG decoding devicethat will receive and decode the converted transport stream.Consequently, the set-top box should not assume any informationpertaining to the external MPEG decoding device. Moreover, conversion ofthe transport stream should be performed only in transport level withoutmodifying any video elementary stream and audio elementary stream.Additionally, conversion of the transport stream should require minimalprocessing power with supporting time-base correction and appropriatedata parsing and re-mapping to ensure interoperability.

An MPEG program may contain a plurality of data streams. These mayinclude the elementary stream (ES), a packetized elementary stream(PES), a transport stream (TS) and a program specific informationstream. An MPEG encoder typically creates the ESs by utilizing one ormore analog video and audio content. The MPEG encoder may be configuredto apply MPEG compression algorithms to the source content, which mayresult in an individual compressed ES for each audio and video stream.This encoded and compressed data stream may be decoded in a set-top boxand viewed on a TV. Factors such as a bit rate of the encoded stream,quality of the original source content and encoder algorithm maytypically determine the quality of the output signal. Notably, the typeof encoding may determine whether another system will be able to decodeand interpret a received MPEG data stream. In this regard, the othersystem may be a legacy or disparate system.

In a typical MPEG data stream, the length of individual ESs may beequivalent to the length of the program. Each ES may contain a pluralityof variable-length packets called a PES. The PES may include a headerthat may precede one or more payload bytes. The header may includeinformation pertaining to the encoding process required by the MPEGdecoder to decompress and decode a received ES. Each individual ES mayhave a corresponding PES and any encoded audio and video information maystill reside in separate PESs. Notably, the PES may be viewed primarilyas a logical construct and is not intended to be utilized for datainterchange, transport, and interoperability. Notwithstanding, the PESmay be utilized for conversion between transport streams (TSs) andprogram information streams (PSs).

The TS and PS may be formed by multiplexing a plurality of PES packets.The TS may include a plurality of additional packets that may containtables, which may be utilized for de-multiplexing the TS. The tables maybe collectively called program specific information (PSI). To maintainsynchronization and timing, null packets may also be inserted to fillthe intervals between information-bearing packets. These null packetsmay contain dummy payload data and timing information for theirassociated program. The timing information may be called the programclock reference (PCR). The PCR may be located in one of the optionalheader fields of the TS packet. During operation, the PCR may permit thedecoder to synchronize its clock to the same frequency as that of theoriginal encoder's clock frequency. TS packets may have a fixed lengthof 188 bytes, which may include a header having a minimum size of 4bytes and a maximum payload of 184 bytes.

FIG. 1 is a diagram of the structure for an exemplary MPEG transportstream 100. Referring to FIG. 1, TS 100 may include a header 102 andpayload 104. Header 102 may include the following fields:synchronization (SYNC) 106, transport error indicator 108, payload unitstart indicator 110, transport priority 112, packet ID (PID) 114,transport scrambling control 116, adaptation field control 118,continuity counter 120, adaptation field 122, and a plurality of PES,namely PES1 124, PES2 126, . . . , PESn 130. The adaptation field 118may further include the following fields: adaptation field length 132,discontinuity indicator 134, random access indicator 136, PES priority138, flags 140, optional fields 142 and stuffing bytes 144. The optionalfields 142 may further include the following: program clock reference(PCR) 146, OPCR 148, a splice countdown 150, private data length 152,adaptation field extension length 154, flags 156 and optional field 158.

The TS 100 may include variable length PES that may be divided intofixed length packets for use by a transmission system. In this regard,the information added by the TS is additional to the informationcontained in the headers of the PESs. SYNC byte 106 may be used todelineate the beginning and ending of TS packet 100. The transport errorindicator 108 may indicate when there is an error in a packet or block.This may be particularly useful for error block testing. PID 114 may bea unique identifier that may identify every video and audio stream.Additionally, each PSI table may have a unique PID 114. The PID 114 maybe utilized for identifying a channel and may include any informationrequired for locating, identifying and reconstructing programs. SomePIDs are reserved for specific uses by the MPEG protocol. PID values maybe stored in PSI tables. In order to ensure that all the audio, videoand data for a program are properly decoded, it may be critical toensure that the PIDs are correctly assigned and that the PSI tablescorrespond with their associated audio and video streams.

PCR 146 may have 42 bits, 9 bits of which may be incremented at 27 MHzand 33 bits that may be incremented at 90 kHz upon rollover of the 9bits. The bits in PCR 146 may provide program clock recovery informationthat may be utilized for synchronization. PCR 146 may be used to providea clock recovery mechanism for MPEG programs. A 27 MHz system time clock(STC) signal may typically be used for encoding MPEG signals. Decodingof the signal requires a clock that may be locked to the encoder's STCof 27 MHz. Notably, the PCR 146 may be utilized by the decoder toregenerate a local clock signal that is locked to the STC. Whenever aprogram is placed in the transport stream, a 27 MHz time stamp may beinserted into the PCR 146. When the signal is received by a decoder, thedecoder may compare the value in the PCR 146 with the frequency of itslocal voltage controlled oscillator (VCO) and adjust the VCO to ensurethat the VCO is locked to the frequency specified by the PCR 146. Toensure accuracy, the PCR 146 may be updated with the STC every about 100ms.

The continuity counter (CC) 120 may be used to determine when packetsare lost or repeated. It may include a 4-bit field, which may berepeatedly incremented from zero to 15 for each PID. Discontinuitycounter 134 may permit a decoder to handle discontinuities in thetransport stream. Discontinuity counter 134 may indicate a time basesuch as the PCR 146 and continuity counter 120 discontinuities. Randomaccess indicator 136 may be configured to indicate whether the next PESpacket in the PID stream contains a video-sequence header or the firstbyte of an audio frame. Splice countdown 150 may be configured toindicate the number packets of the same PID number to a splice pointoccurring at the start of PES packets.

Two or more MPEG TSs may be multiplexed to form a multiprogram TS. In acase where the TC may include a single MPEG TS, the output of themultiplexer may be called a single program TS (SPTS). Furthermore, anumber of SPTSs may be multiplexed to create a multiprogram TS. In somecases, the program may include one or more ESs that may have a similartime reference. This may occur, for example, in a movie that has videoand its corresponding audio content.

PSI may include a set of tables that may be part of a TS. The tables inthe PSI may be required while de-multiplexing the TS and for matchingPIDs to their corresponding programs. Once the PIDs are matched to theircorresponding programs, the TS may be decoded by assembling anddecompressing program contents. Typically, in order to determine whichaudio and video PIDs contain the corresponding content for a particularprogram, a program map table (PMT) may be decoded. Each program may haveits own PMT bearing a unique PID value. The PAT may be decoded in orderto determine which PID contains the desired program's PMT. The PAT mayfunction as the master PSI table with PID value always equal to. In acase where the PAT cannot be found and decoded in the TS, no programsmay be available for presentation.

The PSI table may be refreshed periodically at a rate that is fastenough to allow a set-top box to go through program recovery anddecompression processes. This may be necessary to ensure real-time userinteraction. The PSI may also be used to determine the accuracy andconsistency of PSI contents. Notwithstanding, during programs changes ormodification of multiplexer provisioning, there may be packets whichhave a PID value present in the TS, but have no corresponding referencein the PSI. Additionally, the PSI may have references to one or morepackets in the PID that are not present in the TS.

In existing MPEG compliant systems, audio/video services may be carriedusing some or all of the 188 bytes of the packet, called transportpackets. Multiple services may be differentiated using a packetidentifier (PID) contained in a packet header called the transportpacket header. Transport packets from various services may bemultiplexed and transmitted on the same physical medium. Exemplary mediamay include, copper, coaxial cable, wireless, optical and anycombination thereof. On the receiver side transport packets may bede-multiplexed and data may be separated for each service. For example,audio packets may be separately de-multiplexed from video packets.

Transport packets may include three fields, namely a 4-byte header, anoptional adaptation field and a packet payload. The packet payload maynot be altered by multiplexing or transmitting equipment, except duringprocessing which may include data encryption and decryption. Ingenerally, encryption may be done once within a typical MPEG processingsystem. Notwithstanding, some fields of adaptation field may be changedby multiplexing and transmission equipment. Typically, packet orderwithin a PID channel may be maintained from an MPEG encoder to an MPEGreceiver but packet order among multiple PID streams may not beguaranteed during transmission by any transmitting equipment. In caseswhere co-relation of packets from different PIDs may be required, packetposition in a stream cannot be utilized since packet order amongmultiple PID channels may be altered.

FIG. 1A is a block diagram of an exemplary MPEG encoding system 14.Referring to FIG. 1A, an analog input signal may be converted to digitalformat by A/D converter 16. An output signal from the A/D converter 16may be communicated to video processor 18 for processing. After thevideo processor 18 processes the signal, the output signal generatedfrom the video processor 18 may be sent to a sub-picture encoder 24 forprocessing. A presentation control information (PCI) encoder 26 may beconfigured to encode PCI data for the video signal processed by videoprocessor 22. The output signal generated from the video processor 18may also be received and processed by an MPEG video encoder 28 which maybe configured to format the video signal in MPEG format.

An analog input audio signal may be converted to digital format by A/Dconverter 20. An output signal from the A/D converter 20 may becommunicated to audio processor 22 for processing. After the audioprocessor 22 processes the signal, the output signal generated from theaudio processor 22 may be sent to an audio encoder 30 to be encoded in asuitable format. A data search information (DSI) encoder 34 may beconfigured to encode indexing and search data for the video signalprocessed by video processor 22. The outputs from the sub-pictureencoder 24, PCI encoder 26, MPEG video encoder 28, audio encoder 30 andDSI encoder 34 may be multiplexed into a single data stream, bymultiplexer 36. A controller 32 may be configured to control theoperations of audio encoder 32, DSI encoder 34 and multiplexer (MUX) 36.The output of the MUX 36 may include a single steam, which may containvarious kinds of PES. The PES may include, audio, video, PCI, DSI andsub-picture information.

The MPEG encoding system 14 may also include a conditional access buffer38 that may be configured to controls propagation of the packets throughMUX 36. A track buffer 40 may be used to buffer and assemble datapackets for further processing. Finally, the assembled packets may beencoded with a forward error correction algorithm within the forwarderror correction block (FEC) 42 for transmission over a channel. Theoutput of the FEC block 42 may be an MPEG formatted digital audio/videosignal.

FIG. 1B is a block diagram of an exemplary MPEG decoding system 48. MPEGdecoding system 48 may be, for example, a set-top box. Referring to FIG.1B, MPEG decoding system 48 may include a forward error correctionprocessing block 50 and a track buffer 52. The track buffer 52 may beused to buffer and assemble data packets for further processing. Thepackets may be processed by a conditional access circuit 54 that may beconfigured to control propagation of the packets through de-multiplexer(DEMUX) 56 and into respective video and audio processing paths. Theoutput of the DEMUX 56 may include various kinds of packetizedelementary streams (PES), including audio, video, presentation controlinformation (PCI), sub-picture information, and data search information(DSI) streams. The de-multiplexed PCI in the PES may be buffered priorto being decoded by PCI decoder 66.

The sub-picture information in the PES may be buffered and decoded bysub-picture decoder 68. The de-multiplexed video stream in the PES maybe decoded by MPEG video decoder 64. Video processor 72 may beconfigured to process the output from the MPEG video decoder 64. Videoprocessor 72 may be a microprocessor or an integrated circuit (IC).Subsequent to processing of the MPEG video, mixer 70 may combine theoutputs of the PCI decoder 66, the video processor 64 and thesub-picture decoder 68 to form a composite video signal. The output ofmixer 70 may thereafter be encoded in a conventional television signalformat such as PAL, SECAM, or NTSC by the TV encoder 76. The output ofthe TV encoder 76 may be a digital video signal. However, D/A converter78 may convert this digital video output signal to an analog videooutput signal.

The audio portion of the PES may be buffered and decoded by audiodecoder 62. The output of the audio decoder 62 may be a digital audiosignal. The audio D/A 74 may process digital audio received from theaudio decoder 62 and produce an analog audio output signal. Audiodecoder 62 may include a frame buffer sufficient for temporarily storingaudio frames prior to decoding. Controller 60 may control the operationof audio decoder 62 and DSI 58. Controller 60 may be configured toutilize DMA to access to data in track buffer 52 or any other associatedmemory (not shown).

FIG. 2 is block diagram 200 illustrating an exemplary DSS transportstream packet 202. Referring to FIG. 2, there is shown a DSS transportstream packet 202. The DSS transport stream packet 202 may include aprefix portion 208 and a payload portion 210. The prefix portion 208 ofthe DSS transport stream packet 202 may contain two (2) bytes, while thepayload portion 210 may contain 128 bytes. The DSS transport streampacket 202 may have 130 bytes per packet. An additional seventeen bytesfollowing the end of the payload portion may be utilized for forwarderror correction (FEC) 212. The two (2) byte prefix may include a 12-bitservice channel identification (SCID) 214, which may be adapted todefine one of channels 0 through 4095 to which a packet may belong. TheSCID 214 may be analogous to the PID 114 (FIG. 1) of an MPEG frame.Following the SCID 214, various flag fields may define a type ofencryption utilized by the packet. Each flag may be four (4) bits.

FIG. 3 is block diagram 300 illustrating the conversion of a DSStransport stream packet to a DVB transport stream packet in accordancewith an embodiment of the present invention. Referring to FIG. 3, thereis shown a DSS transport stream packet 302 and DVB transport streampacket 304 prior to start of the conversion process. DVB transportstream packet 306 is the resultant MPEG-2 compliant packet after theconversion process.

The DSS transport stream packet 302 may include a prefix portion 308 anda payload portion 310. The prefix portion 308 of the DSS transportstream packet 302 may contain two (2) bytes, while the payload portion310 may contain 128 bytes. The DSS transport stream packet 302 may have130 bytes per packet. The DVB transport stream packet 304 may include aheader portion 312 and a payload portion 314. The header portion 312 ofthe DVB transport stream packet 304 may contain at least four (4) bytes,while the payload portion 310 may contain a maximum of 184 bytes. Thesize of the header of the DVB transport stream packet 304 may bedependent on an associated adaptation field length 132 (FIG. 1). The DVBtransport stream packet 304 may have 188 bytes per packet.

In accordance with an embodiment of the invention, an adaptation field326 consisting of the difference between the payload 310 of the DSStransport stream packet 302 and the payload 314 of the DVB transportstream packet 304 may be created within the header 322 of the DVBtransport stream packet 320. In this case, the adaptation field 326 maycontain (184-128) bytes or 56 bytes. Since the header field originallyhad an initial size of at least four (4) bytes, the addition of the 56bytes of the adaptation field results in a header size of at least 60bytes. Other information such as the PCR and/or stuffing bytes may beadded to the adaptation filed 326 of the header 322, thereby increasingits size accordingly. The 128 bytes of the DSS transport stream packetpayload 314 may be mapped into the 128 bytes of the DVB transport streampacket payload 324.

Since the DSS transport stream packet 302 contains a 12-bit SCID and theDVB transport stream packet 304 contains a 13-bit PID, an appropriatemapping scheme may be utilized to map the 12-bit SCID into the 13-bitPID. Additionally, since some of the SCIDs utilized by the DSS may havespecific reserved values, it may not be syntactically correct to utilizesome of these SCIDs in the PID field of a DVB transport stream packet.In accordance with an embodiment of the invention, whenever a SCID liesbetween 0x02 and 0x0F, an offset value of 0x30 may be added to the SCIDand the result placed in the PID field of the converted DVB transportstream packet. For example, video SCID 0x0a will have a resultant videoPID of 0x3a, and audio SCID 0x0b will have a resultant audio PID of0x3b. The offset value may be chosen based on the TS stream so thatthere is no conflict PID within such TS.

Other parameters in the header 222 may also require modification. Forexample, each DVB transport stream packet may have an associated 4-bitcontinuity counter (CC), and various transport header flags such as thepayload unit start indicator may be initialized to appropriate values.

Regarding DSS transport stream packets, a relative time tagged sequence(RTS) may be found in auxiliary transport stream data packets. The RTSin a DSS transport stream packet may be analogous to the PCR in a DVBtransport stream packet. Consequently, the RTS values utilizes remappingand insertion. The RTS values utilized by the DSS transport stream is a40-bit value which may represent time defined by a 27 MHz resolution.The DVB PCR utilized by the DVB transport stream may be located in theadaptation field and is a 33 bit value which may represent time definedby a 90 KHz resolution. In accordance with the invention, an additional7-bit extension may be utilized to represent time as defined by a 27 MHzresolution. The adaptation field extension length may be utilized toindicate the 7-bit extension.

Although a DSS transport steam does not require PES headers to bealigned with transport headers, DVB requires PES headers to be alignedwith the transport header boundaries. In accordance with an aspect ofthe invention, during conversion of a DSS transport stream packet to aDVB transport stream packet, it may be necessary to search for PESheaders and validate each PES header found. This will ensure that thePES header is synchronous with the transport headers in the resultingDVB packet.

DSS audio transport stream packets may be formatted in any of severalways. Notwithstanding, audio transport streams may, in certaininstances, not require a PES layer. In that case, an ES may be placeddirectly in a DSS transport stream. Accordingly, additional processingmay be required while converting a DSS audio transport stream packetinto a DVB audio transport stream packet. For example, more advancedaudio parsing may be utilized to create ES DVB audio transport streampackets.

In order to provide proper timing and lip synchronization whiletranscoding a DSS transport stream to a DVB transport stream, it may notbe necessary to rewrite PTS/DTS for audio and video data. In accordancewith an aspect of the invention, upon initial acquisition of a PCRvalue, subsequent PCR values may be determined based on a definedtransport stream bit rate. In this regard, any lip synchronizationinherent in the original audio/video transport stream may be maintainedin the resultant converted DVB transport stream. In one aspect of theinvention, PCR may have an initial default value of zero (0). Uponreading one audio PTS or video PTS, PCR may be set to a value offset by0.2 s from the first read-in PTS. In this regard,initial_PCR=(First_Read_In_PTS−0.2) seconds (s). For example, if theFirst_Read_In_PTS=1.5 s, then initial_PCR=(1.5-0.2)=1.3 s. Calculationsmay be based on a 27 MHz clock tick and PCR may be adapted to have a 42bit resolution.

The PCR may be updated based on a user specified TR output bit rate. PCRmay be updated after the output of a single video packet or audiopacket. In a DVB transport stream, PCR packets interval should be lessthan 0.1 s. However in a DSS transport stream, PCR packet intervals maybe larger than 0.1 s. Accordingly, a current PCR value may be comparedagainst a previous packet's PCR, and in a case where the difference isgreater than about 0.08 s for example, an additional PCR packet may beoutput to the TS stream.

FIG. 4 is a block diagram 400 of an exemplary system for converting aDSS transport stream to a DVB transport stream in accordance with anembodiment of the invention. Referring to FIG. 4, there is shown aparser block 404, an input buffer block 406, a video data buffer block408, an audio data buffer block 410, a null packet generator 412, a ratedeterminator 414, and a multiplexer (MUX) 416. DSS transport stream 402serves as an input to the parser block 404 and the DVB transport stream418 is a resultant converted output produced by the MUX 416.

The parser block 404 may include at least a processor function having atleast suitable software for parsing packets in the input DSS transportstream. In this regard, the parser block 404 may be adapted to parse theSCID from packets in the input DSS transport stream 402. The SCID maycorrelate each packet in the input DSS transport stream 402 to aparticular channel. The output of the parser block 404 may be coupled toan input of the buffer block 406.

The input buffer block 403, video data buffer block 408 and audio databuffer block 410 may include any suitable random access memory (RAM),which may include, but is not limited to, static RAM (SRAM), dynamic RAM(DRAM), dual data rate RAM (DDR) and video (VRAM). The input bufferblock 403, video data buffer block 408 and audio data buffer block 410may utilize suitable high speed memory and logic that may be adapted tominimize any effects of processing latency.

At least one output of the input buffer block 406 may be coupled to aninput of the video data buffer block 408. The at least one output of theinput buffer block 406 coupled to the input of the video data bufferblock 408, may be adapted to facilitate transfer video packets from theinput buffer block 406 to the video data buffer block 408. At least oneoutput of the input buffer block 406 may be further coupled to an inputof the audio data buffer block 410. The at least one output of the inputbuffer block 406 coupled to the input of the audio data buffer block410, may be adapted to facilitate transfer audio packets from the inputbuffer block 406 to the audio data buffer block 410.

An output of each of the video data buffer 408 and audio data buffer 410may be coupled to an input of the MUX 416. Rate determinator 414 andnull packet generator 412 may also be coupled to the multiplexer 416.The multiplexer 416 may be adapted to multiplex processed audio andvideo packets and also null packets generated by the null packetgenerator 212. The rate determinator 414 may be adapted to determinewhether an instantaneous bit rate corresponds with a specified bit rateof the converted DVB transport stream. In conjunction with the ratedeterminator 414, the null packet generator 412 may generate one or morenull packets which may be multiplexed into the converted output DVBtransport stream 418 in order to maintain a specified bit rate.

In operation, the input DSS transport stream 402 may be received by theparser block 404. The parser block 404 may parse the incoming DSS inputtransport stream 402 based on the SCID of the packets in the DSS inputtransport stream 202. Since the SCID correlates packets to a particularchannel, packets for a particular channel may be sent to, for example,various channel processing queues maintained in the input buffer 406.Accordingly, based on whether a packet is a video packet or data packet,the packets may be buffered in video data buffer 408 and audio databuffer 410 respectively, for processing.

The video and audio packets may be multiplexed by multiplexer 416 toform the output DVB transport stream 418. In order to maintain aspecified data rate, the rate determinator 414 may be adapted todetermine the data rate of the processed packets. Accordingly, the nullpacket generator 412 may be adapted to generate a corresponding amountof null packets required to meet a specified bit rate. The generatednull packets may be multiplexed with the converted DSS transport steampackets to create the DVB transport stream output 418.

The maximum video payload size of a single DSS transport stream packetis 127 bytes. For DSS SD, the video payload may be located in, forexample, an MPEG-2 ES format. To convert or transcode this payload intoan MPEG formatted payload, it may be necessary to remove any redundantdata from the video payload of the transport stream packet. Accordingly,upon receipt of a transport stream packet containing video data,portions of the header information such as a picture header flag HD, maybe saved in various header related variables. If a transport streampacket carries redundant video data, the picture header flag HD may belabeled and at least one additional NB flag may be located. The NB flagmay be adapted to contain redundant data length. After discarding anyredundant bytes of the video transport stream packet, any remaining rawvideo data may be moved to a video data buffer 208 from the input buffer206, the latter of which may be used to search for redundant data.

FIG. 5 is an block diagram of an exemplary video buffer 510 arrangementand an exemplary audio buffer 520 arrangement in accordance with anembodiment of the invention. Referring to FIG. 5, the video data buffer510 may be representative of the video data buffer 408 (FIG. 4). Forillustrative purposed, the video data buffer 510 may be, for example,254 bytes in size so that it may sufficiently accommodate two raw videodata packets, each being 127 bytes. However, the invention is notlimited in this regard and other video buffer sizes may be employedwithout departing from the spirit of the invention. The audio databuffer 520 may be representative of the audio data buffer 408 (FIG. 4).

The audio data buffer 520 may be similar to video data buffer 510.However, the audio data buffer 520 may be adapted to include anadditional three (3) bytes. Typically, DSS packetizes MPEG audio intoMPEG-1 system packets, and AC3 audio into MPEG-2 PES packets. In orderto facilitate the conversion of MPEG-1 packets to MPEG-2 PES packets,three (3) additional bytes may be required. Accordingly, the audio databuffer 520 may be 257 bytes in size.

Referring to the DSS video transport stream packets, PTS/DTS may becarried within picture user data. In the case of a picture header0x0100, the video transport stream packet may be packet aligned and thepicture header may be toggled by the header flag HD. Thus for eachpicture header packet, upon locating the user data header 0x1B2, thePTS/DTS may be extracted. In order to locate the user data header 0x1B2with the greatest accuracy and statistical probability, packet headersmay be searched across the packet header's upper boundary 512, to apacket boundary of a successive video transport stream packet. If a userdata header packet is found, a position or location indicating a firstbyte of user data header 0x1B2 may be noted for future datamanipulation. Reference 514 may represent the largest length of videouser data given an upper bound of the search header 512.

Subsequent to searching the header to locate the user data header, thePTS/DTS video for the corresponding video transport stream packet may beread from video transport stream data packet. In the case of DSS, sincethe clock rate is 27 MHz, PTS/DTS has a 32-bit resolution. However, inthe case of DVB, since the clock rate is 90 KHz, PTS/DTS has a 33-bit ofresolution. Accordingly, any retiming function utilized may requirechecking of two loopback boundaries. The first loopback boundary may beutilized for DSS. In the case of DSS, if a counter utilized for theclock loops back from 232 to zero (0), then it may be appropriate toensure that resulting exemplary parameters such as mpegPTS/mpegDTS doesnot loop back, but incremented to its proper value. It should berecognized that after the mpegPTS parameter has been incremented, itsvalues may be negative due to an MPEG video reorder process. Thus, inthe case of a parameter dssPTS, loopback may occur from an upperboundary of 2³² to a lower boundary of zero (0) or vise versa. Forparameter mpegDTS, the increment may always be positive. Consequently,in the case of parameter dssDTS, loopback may only happen from the upperboundary 2³² to the lower boundary of zero (0). In the case of MPEG, asan illustration, parameters or variables such as mpegPTS and/or mpegDTSmay be saved as 27 MHz, thereby ensuring a loopback boundary of 2⁴²instead of 2³³. In this case, the conversion from 27 MHz to 90 KHz mayoccur prior to the video PTS/DTS output.

Conversion of a video ES to a corresponding video PES may be achieved byinserting a PES header before each picture header 0x100. For video, aPES length may be set to zero (0), which is permitted by the MPEGspecification. Before the PES, a value of 0xFF may be inserted in thestuffing byte of the adaptation field. Time stamps corresponding to thePTS/DTS value may be converted from 27 MHz to 90 KHz and subsequentlyplaced in the transport stream. In transport stream header, a parametersuch as a payload_unit_start_indicator may be set to a value of, forexample one (1), for the packet containing the PES header. In the caseof DSS, it may be permissible for both the PTS and DTS values to besimilar, and in that case, both values corresponding to PTS and DTS maybe transferred. However, in the case of MPEG, if a PTS value isequivalent to a DTS value, then only PTS itself will be transferred inthe transport stream.

In the case of DSS, audio may be carried in MPEG-1 or MPEG2 PES using asimilar structure. Furthermore, no payload packet alignment may berequired for audio. Thus, an audio header may cross the boundary of anytwo audio transport stream data packets. Therefore, it may be necessaryto search the header of each audio packet and an upper boundary may beset to the last byte of the first audio data packet. This may guaranteethat any cross packet headers may be found with a high statisticalprobability. In the case of DVB audio, the header is 0x1C0 and for AC3audio, the header is 0x1BD.

Since the header values 0x1C0 and 0x1BD may be contained in an audiopayload, not every value of 0x1C0 and 0x1BD found may represent andappropriate header. For example, not every 0x1C0 and 0x1BD within audiodata packet are audio packet headers, since perchance, it may be actualpayload data. Accordingly, each audio header found in an initial searchmay be rechecked to ensure its authenticity. In the case of MPEG audio,it may be appropriate to search for the first two payload bytesfollowing the header once a value of 0x1C0 is found. If the first twopayload bytes following the value 0x1C0 contains an MPEG audio startcode 1xFFF, then the value of 0x1C0 may be a genuine audio header.Otherwise, it may not be a genuine header value and the search for anactual header value should continue.

In the case of AC3 audio, the search may be more involved since a PESheader can be of any length. Accordingly, it might not be sufficient tosearch the first two bytes of the payload, since the header values mayexist beyond the boundary of two data packets. From a practicalperspective, the chances of this occurring may be statistically remote.Consequently, it may be appropriate to utilize a method similar to thatused for searching for header 0x1C0 as previously described. In order toverify header 0x1BD, reserved flags following header 0x1BD may becompared to determine whether there may be consistent with MPEG-2syntax.

DSS MPEG audio's PTS has resolution of 33 bits, which is the similar tothat of MPEG. However, the clock rate for DSS is 27 MHz instead of 90KHz. In general, audio PTS increment may be positive since there is noaudio frame reordering. In the case of DSS, AC3 audio's PTS has aresolution of 32 bits. As a result, the processing may be similar tothat of DSS MPEG audio.

Based on the MPEG standard, a PES header should be packet aligned withina transport stream packet payload whenever a parameter such as apayload_unit_start_indicator has been set. In one aspect of theinvention, in the case of DSS, the payload may not be packet aligned. Inthis case, once an audio header 0x1C0 or 01xBD has been located in thefirst audio data packet, one transport stream packet containing theaudio data may be generated before the audio header. In another aspectof the invention, in the case of MPEG audio, stuffing bytes, for example0xFF, after audio header may be discarded and an additional PES packetflag byte need to be inserted. In an embodiment of the invention, 3additional PES packet flag bytes may be inserted. However, the inventionis not limited in this regard. In a case where additional PES packetflag bytes may be inserted, the PES packet length will change.Accordingly, in both MPEG and AC3 audio, the PES packet length may beadjusted since a PES length 0x00may only be permitted in the case ofvideo. Any remaining data may be repositioned within audio data buffer.

In certain instances, packet reordering may be utilized. Since each databuffer may be adapted to hold two data packets, the output order ofaudio and video packet might be changed. However, for audio or videoalone, the data packet may maintain its original order and in this case,reordering may not be necessary. For example, if A denotes an audiopacket and V denotes a video packet, given the following input transportstream data sequence:

-   -   VAVVAVVVVVAVVVAVVVA,        a corresponding output sequence, neglecting the insertion of        null packets, may be:    -   VVVVVVAVVVAVVVAVAVA.

A null packet may be inserted whenever a transport stream output cannotmeet a specified bit rate. For example, an algorithm based on a videopicture header and video frame rate may be utilized to determine aninstantaneous bit rate. For a specified transport stream, assuming a bitrate of, for example ts_rate, the total output bits between each pictureis ts_rate/frame_rate (bit). In this case, the algorithm may be adaptedto determine the picture header count and accordingly determine anappropriate number of bits which may be required to properly adjust thebit rate. If the instantaneous bit rate is less than the specified bitrate, then null packets may be inserted.

In light of the foregoing, the invention provides a method and systemfor converting a DSS transport stream to a DVB transport stream. Inaccordance the invention, the packet length of the 130-byte DSS framemay be extended or encapsulated into a 188-byte DVB frame. Additionally,various parameters such as the SCID and the RTS may have to be remappedinto appropriate DVB parameters such as PID and PCR respectively.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in one computersystem, or in a distributed fashion where different elements are spreadacross several interconnected computer systems. Any kind of computersystem or other apparatus adapted for carrying out the methods describedherein is suited. A typical combination of hardware and software may bea general-purpose computer system with a computer program that, whenbeing loaded and executed, controls the computer system such that itcarries out the methods described herein.

The present invention also may be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

Notwithstanding, the invention and its inventive arrangements disclosedherein may be embodied in other forms without departing from the spiritor essential attributes thereof. Accordingly, reference should be madeto the following claims, rather than to the foregoing specification, asindicating the scope of the invention. In this regard, the descriptionabove is intended by way of example only and is not intended to limitthe present invention in any way, except as set forth in the followingclaims.

1. A method for converting a DSS transport stream to a DVB transportstream, the method comprising: encapsulating at least a prefix portionand a payload portion of a DSS transport stream packet into at least aheader portion and a payload portion of a DVB transport stream packet;mapping at least a portion of said prefix portion and said payloadportion of said DSS transport stream packet into at least a portion ofsaid header portion and said payload portion of said DVB transportstream packet; and aligning at least a portion of said payload of saidDSS transport stream packet with at least a portion of said payloadportion of said DVB transport stream packet, wherein said encapsulatingcomprises creating an adaptation field within at least a portion of saidheader portion to increase the size of said DVB transport stream packet.2. The method according to claim 1, wherein said adaptation field is atleast fifty six (56) bytes in size.
 3. The method according to claim 1,wherein said mapping comprises mapping at least an SCID of said DSStransport stream packet into a PID of said DVB transport stream packet.4. The method according to claim 1, wherein said mapping comprisesmapping at least an RTS of said DSS transport stream packet into a PORof said DVB transport stream packet.
 5. The method according to claim 1,wherein said mapping comprises mapping at least a PTS and DTS resolutionof said DSS transport stream packet into a corresponding PTS and DTSresolution of said DVB transport stream packet.
 6. The method accordingto claim 1, wherein said aligning comprises: locating PES headers insaid DSS transport stream packet; and validating said located PESheaders to ensure that said headers are synchronous with transportheaders of said DSS transport stream packet.
 7. The method according toclaim 1, comprising inserting at least one null packet in at least oneof said header portion and said payload portion of said DVB transportstream packet to maintain a specified data rate.
 8. A machine-readablestorage, having stored thereon a computer program having at least onecode section for converting a DSS transport stream to a DVB transportstream, the at least one code section executable by a machine forcausing the machine to perform the steps comprising: encapsulating atleast a prefix portion and a payload portion of a DSS transport streampacket into at least a header portion and a payload portion of a DVBtransport stream packet; mapping at least a portion of said prefixportion and said payload portion of said DSS transport stream packetinto at least a portion of said header portion and said payload portionof said DVB transport stream packet; and aligning at least a portion ofsaid payload of said DSS transport stream packet with at least a portionof said payload portion of said DVB transport stream packet, whereinsaid at least one code section for encapsulating comprises code forcreating an adaptation field within at least a portion of said headerportion to increase the size of said DVB transport stream packet.
 9. Themachine-readable storage according to claim 8, wherein said adaptationfield is at least fifty six (56) bytes in size.
 10. The machine-readablestorage according to claim 8, wherein said at least one code section formapping comprises code for mapping at least an SCID of said DSStransport stream packet into a PID of said DVB transport stream packet.11. The machine-readable storage according to claim 8, wherein said atleast one code section for mapping comprises code for mapping at leastan RTS of said DSS transport stream packet into a PCR of said DVBtransport stream packet.
 12. The machine-readable storage according toclaim 8, wherein said at least one code section for mapping comprisescode for mapping at least a PTS and DTS resolution of said DSS transportstream packet into a corresponding PTS and DTS resolution of said DVBtransport stream packet.
 13. The machine-readable storage according toclaim 8, wherein said at least one code section for aligning comprises:code for locating PES headers in said OSS transport stream packet; andcode for validating said located PES headers to ensure that said headersare synchronous with transport headers of said DSS transport streampacket.
 14. The machine-readable storage according to claim 8,comprising code for inserting at least one null packet in at least oneof said header portion and said payload portion of said DVB transportstream packet to maintain a specified data rate.
 15. A system forconverting a DSS transport stream to a DVB transport stream, the systemcomprising: at least one encapsulator adapted to encapsulate at least aprefix portion and a payload portion of a DSS transport stream packetinto at least a header portion and a payload portion of a DVB transportstream packet; at least one mapper adapted to map at least a portion ofsaid prefix portion and said payload portion of said DSS transportstream packet into at least a portion of said header portion and saidpayload portion of said DVB transport stream packet; and at least onealigner adapted to align at least a portion of said payload of said DSStransport stream packet with at least a portion of said payload portionof said DVB transport stream packet, wherein said at least oneencapsulator creates an adaptation field within at least a portion ofsaid header portion to increase the size of said DVB transport streampacket.
 16. The system according to claim 15, wherein said adaptationfield is at least fifty six (56) bytes in size.
 17. The system accordingto claim 15, wherein said at least one mapper maps at least an SCID ofsaid DSS transport stream packet into a PID of said DVB transport streampacket.
 18. The system according to claim 15, wherein said at least onemapper maps at least an RTS of said DSS transport stream packet into aPCR of said DVB transport stream packet.
 19. The system according toclaim 15, wherein said at least one mapper maps at least a PTS and DTSresolution of said DSS transport stream packet into a corresponding PTSand DTS resolution of said DVB transport stream packet.
 20. The systemaccording to claim 15, wherein said at least one aligner comprises: alocator adapted to locate PES headers in said DSS transport streampacket; and a validator adapted to validate said located PES headers toensure that said headers are synchronous with transport headers of saidDSS transport stream packet.
 21. The system according to claim 15,comprising at least one null packet generator adapted to insert at leastone null packet in at least one of said header portion and said payloadportion of said DVB transport stream packet to maintain a specified datarate.
 22. A method for processing signals in a communication system, themethod comprising: converting a DSS transport stream packet to a DVBtransport stream packet, wherein said conversion comprises: modifying asize of a header portion of said DVB transport stream packet and a sizeof said a payload portion of said DVB transport stream packet, therebyincreasing the size of said DVB transport stream packet; and mapping aprefix portion of a DSS transport stream packet into said modifiedheader portion a DVB transport stream packet, and a payload portion ofsaid DSS transport stream into said modified payload portion of said DVBtransport stream.
 23. The method according to claim 22, comprising:increasing said size of said header portion of said DVB transport streampacket; and decreasing said size of said payload portion of said DVBtransport stream packet.
 24. The method according to claim 22,comprising increasing said size of said header portion of said DVBtransport stream packet by at least an amount equal to a differencebetween a size of said payload portion of said DSS transport streampacket and said size of a payload portion of said DVB transport streampacket.
 25. The method according to claim 22, comprising inserting anadaptation field within said modified header portion of said DVBtransport stream packet.
 26. The method according to claim 25, whereinsaid inserted adaptation field comprises one or more of an adaptationfield length, a discontinuity indicator, a random access indicator, aPES priority, a flags field, optional fields and stuffing bytes field.27. The method according to claim 26, wherein said optional fieldscomprise at least a PCR, an OPCR, a flags field and an optional field.28. The method according to claim 25, wherein said inserted adaptationfield is at least fifty six (56) bytes in size.
 29. The method accordingto claim 22, comprising mapping an SCID of said DSS transport streampacket into a PID of said DVB transport stream packet.
 30. The methodaccording to claim 29, comprising parsing said DSS transport streampacket based on said SCID.
 31. The method according to claim 22,comprising mapping an RTS of said DSS transport stream packet into a PCRof said DVB transport stream packet.
 32. The method according to claim22, comprising mapping at least a PTS and DTS resolution of said DSStransport stream packet into a corresponding PTS and DTS resolution ofsaid DVB transport stream packet.
 33. The method according to claim 22,comprising locating PES headers in said OSS transport stream packet. 34.The method according to claim 33, comprising validating said located PESheaders in said DSS transport stream to synchronize said located PESheaders with transport headers of said DSS transport stream packet. 35.The method according to claim 22, comprising inserting at least one nullpacket in one or more of said header portion of said DVB transportstream packet and said payload portion of said DVB transport streampacket to maintain a specified data rate.
 36. The method according toclaim 35, comprising multiplexing said at least one null packet intosaid DVB transport stream packet.
 37. The method according to claim 22,wherein said DVB transport stream packet comprises a DVB MPEG transportstream packet.
 38. A machine-readable storage, having stored thereon acomputer program having at least one code section for processing signalsin a communication system, the at least one code section executable by amachine for causing the machine to perform the steps comprising:converting a DSS transport stream packet to a DVB transport streampacket, wherein said conversion comprises: modifying a size of a headerportion of said DVB transport stream packet and a size of said a payloadportion of said DVB transport stream packet, thereby increasing the sizeof said DVB transport stream packet; and mapping a prefix portion of aDSS transport stream packet into said modified header portion a DVBtransport stream packet, and a payload portion of said DSS transportstream into said modified payload portion of said DVB transport stream.39. The machine-readable storage according to claim 38, comprising codefor: increasing said size of said header portion of said DVB transportstream packet; and decreasing said size of said payload portion of saidDVB transport stream packet.
 40. The machine-readable storage accordingto claim 38, comprising code for increasing said size of said headerportion of said DVB transport stream packet by at least an amount equalto a difference between a size of said payload portion of said DSStransport stream packet and said size of a payload portion of said DVBtransport stream packet.
 41. The machine-readable storage according toclaim 38, comprising code for inserting an adaptation field within saidmodified header portion of said DVB transport stream packet.
 42. Themachine-readable storage according to claim 41, wherein said insertedadaptation field comprises one or more of an adaptation field length, adiscontinuity indicator, a random access indicator, a PES priority, aflags field, optional fields and stuffing bytes field.
 43. Themachine-readable storage according to claim 42, wherein said optionalfields comprise at least a PCR, an OPOR, a flags field and an optionalfield.
 44. The machine-readable storage according to claim 41, whereinsaid inserted adaptation field is at least fifty six (56) bytes in size.45. The machine-readable storage according to claim 38, comprising codefor mapping an SCID of said DSS transport stream packet into a PID ofsaid DVB transport stream packet.
 46. The machine-readable storageaccording to claim 45, comprising code for parsing said DSS transportstream packet based on said SCID.
 47. The machine-readable storageaccording to claim 38, comprising code for mapping an RTS of said DSStransport stream packet into a PCR of said DVB transport stream packet.48. The machine-readable storage according to claim 38, comprising codefor mapping at least a PTS and DTS resolution of said DSS transportstream packet into a corresponding PTS and DTS resolution of said DVBtransport stream packet.
 49. The machine-readable storage according toclaim 38, comprising code for locating PES headers in said DSS transportstream packet.
 50. The machine-readable storage according to claim 49,comprising code for validating said located PES headers in said DSStransport stream to synchronize said located PES headers with transportheaders of said DSS transport stream packet.
 51. The machine-readablestorage according to claim 38, comprising code for inserting at leastone null packet in one or more of said header portion of said DVBtransport stream packet and said payload portion of said DVB transportstream packet to maintain a specified data rate.
 52. Themachine-readable storage according to claim 51, comprising code formultiplexing said at least one null packet into said DVB transportstream packet.
 53. The machine-readable storage according to claim 38,wherein said DVB transport stream packet comprises a DVB MPEG transportstream packet.
 54. A system for processing signals in a communicationsystem, the system comprising: at least one circuitry that converts aDSS transport stream packet to a DVB transport stream packet, whereinsaid conversion comprises: modifying a size of a header portion of saidDVB transport stream packet and a size of said a payload portion of saidDVB transport stream packet, thereby increasing the size of said DVBtransport stream packet; and mapping a prefix portion of a OSS transportstream packet into said modified header portion a DVB transport streampacket, and a payload portion of said DSS transport stream into saidmodified payload portion of said DVB transport stream.
 55. The systemaccording to claim 54, comprising: increasing said size of said headerportion of said DVB transport stream packet; and decreasing said size ofsaid payload portion of said DVB transport stream packet.
 56. The systemaccording to claim 54, wherein said at least one circuitry increasessaid size of said header portion of said DVB transport stream packet byat least an amount equal to a difference between a size of said payloadportion of said DSS transport stream packet and said size of a payloadportion of said DVB transport stream packet.
 57. The system according toclaim 54, wherein said at least one circuitry inserts an adaptationfield within said modified header portion of said DVB transport streampacket.
 58. The system according to claim 57, wherein said insertedadaptation field comprises one or more of an adaptation field length, adiscontinuity indicator, a random access indicator, a PES priority, aflags field, optional fields and stuffing bytes field.
 59. The systemaccording to claim 58, wherein said optional fields comprise at least aPCR, an OPCR, a flags field and an optional field.
 60. The systemaccording to claim 57, wherein said inserted adaptation field is atleast fifty six (56) bytes in size.
 61. The system according to claim54, wherein said at least one circuitry maps an SCID of said DSStransport stream packet into a PID of said DVB transport stream packet.62. The system according to claim 61, wherein said at least onecircuitry parses said DSS transport stream packet based on said SCID.63. The system according to claim 54, wherein said at least onecircuitry maps an RTS of said DSS transport stream packet into a PCR ofsaid DVB transport stream packet.
 64. The system according to claim 54,wherein said at least one circuitry maps at least a PTS and DTSresolution of said DSS transport stream packet into a corresponding PTSand DTS resolution of said DVB transport stream packet.
 65. The systemaccording to claim 54, wherein said at least one circuitry locates PESheaders in said DSS transport stream packet.
 66. The system according toclaim 65, wherein said at least one circuitry validates said located PESheaders in said DSS transport stream to synchronize said located PESheaders with transport headers of said DSS transport stream packet. 67.The system according to claim 54, wherein said at least one circuitryinserts at least one null packet in one or more of said header portionof said DVB transport stream packet and said payload portion of said DVBtransport stream packet to maintain a specified data rate.
 68. Thesystem according to claim 67, wherein said at least one circuitrymultiplexes said at least one null packet into said DVB transport streampacket.
 69. The system according to claim 54, wherein said DVB transportstream packet comprises a DVB MPEG transport stream packet.